Acoustic Data Pinpoints Critical Arctic Breeding Hotspots for Bowhead Whales

New scientific analysis utilizing acoustic monitoring has identified critical breeding hotspots for endangered bowhead whales within the dynamic environment of the Arctic Ocean. Researchers from the Alfred Wegener Institute's (AWI) Ocean Acoustics Group deployed hydrophones in the Fram Strait, near Spitsbergen, to analyze the vocalizations of the region's bowhead population. This specific population is critically depleted, with current numbers estimated in the low 100s, a significant decline from historical estimates exceeding 25,000 individuals.

The investigation contrasted acoustic activity across two ecologically distinct sites to determine how sea ice recession influences habitat utilization. One recording site was situated northwest of Spitsbergen, an area generally maintaining sea-ice concentrations between 60 to 100 percent during the monitoring period. The second site was located in the Eastern Fram Strait, characterized by predominantly ice-free conditions.

In the ice-covered region northwest of Spitsbergen, researchers documented twelve unique, complex songs between October and April, with song diversity peaking in February near the receding ice edge. This high diversity is interpreted as a strong indicator of increased breeding activity, suggesting this ice-associated location functions as a vital reproductive habitat. Conversely, the ice-free Eastern Fram Strait, while showing regular acoustic presence between 2012 and 2023, yielded only simple contact calls, leading researchers to conclude this section serves primarily as a migratory corridor rather than a breeding ground.

The consistent detection of complex songs between October and April, with a peak during winter months like December and January, reinforces the hypothesis that the Fram Strait is a key overwintering and breeding area for the Spitsbergen population. This finding aligns with the known reliance of bowhead whales on sea ice for protection, particularly from predators such as killer whales, whose movements are restricted by ice sheets. The loss of this ice cover also heightens risks from increased shipping traffic and associated noise pollution.

To manage the extensive audio data, the scientific team employed advanced analytical techniques, including Artificial Intelligence image-recognition methods trained on specific patterns within the whale calls. This detailed acoustic mapping, which isolates breeding areas based on song complexity, establishes a data-driven foundation for targeted conservation strategies aimed at safeguarding this vulnerable Arctic endemic species amid ongoing environmental change.